Robin Mueller
2b9f0a7d53
Some checks failed
Rust/va416xx-rs/pipeline/pr-main There was a failure building this commit
48 lines
2.2 KiB
Markdown
48 lines
2.2 KiB
Markdown
VA416xx Bootloader Application
|
|
=======
|
|
|
|
This is the Rust version of the bootloader supplied by Vorago.
|
|
|
|
## Memory Map
|
|
|
|
The bootloader uses the following memory map:
|
|
|
|
| Address | Notes | Size |
|
|
| ------ | ---- | ---- |
|
|
| 0x0 | Bootloader start | code up to 0x3FFC bytes |
|
|
| 0x3FFC | Bootloader CRC | word |
|
|
| 0x4000 | App image A start | code up to 0x1DFFC (~120K) bytes |
|
|
| 0x21FFC | App image A CRC check length | word |
|
|
| 0x21FFE | App image A CRC check value | word |
|
|
| 0x22000 | App image B start | code up to 0x1DFFC (~120K) bytes |
|
|
| 0x3FFFC | App image B CRC check length | word |
|
|
| 0x3FFFE | App image B CRC check value | word |
|
|
| 0x40000 | End of NVM | end |
|
|
|
|
## Additional Information
|
|
|
|
As opposed to the Vorago example code, this bootloader assumes a 40 MHz external clock
|
|
but does not scale that clock up. It also uses a word (4 bytes) instead of a half-word for the CRC
|
|
and uses the ISO 3309 CRC32 standard checksum.
|
|
|
|
This bootloader does not provide tools to flash the NVM memories by itself. Instead, you can use
|
|
the [flashloader](https://egit.irs.uni-stuttgart.de/rust/va416xx-rs/src/branch/main/flashloader)
|
|
application to perform this task using a CCSDS interface via a UART.
|
|
|
|
The bootloader performs the following steps:
|
|
|
|
1. The application will calculate the checksum of itself if the bootloader CRC is blank (all zeroes
|
|
or all ones). If the CRC is not blank and the checksum check fails, it will immediately boot
|
|
application image A. Otherwise, it proceeds to the next step.
|
|
2. Check the checksum of App A. If that checksum is valid, it will boot App A. If not, it will
|
|
proceed to the next step.
|
|
3. Check the checksum of App B. If that checksum is valid, it will boot App B. If not, it will
|
|
boot App A as the fallback image.
|
|
|
|
You could adapt and combine this bootloader with a non-volatile memory to select a prefered app
|
|
image, which would be a first step towards an updatable flight software.
|
|
|
|
Please note that you *MUST* compile the application at slot A and slot B with an appropriate
|
|
`memory.x` file where the base address of the `FLASH` was adapted according to the base address
|
|
shown in the memory map above. The memory files to do this were provided in the `scripts` folder.
|